Conventionally, cellular telephones have become widespread which include a browser function enables Web sites on the Internet to be browsed using the cellular telephone. Currently, among these cellular telephones, such telephones have become popular that have the browser function capable of browsing principally Web sites created for cellular telephones. In recent years, cellular telephones have begun to spread widely which have the browser function (so-called full-browser function) capable of browsing Web sites created for personal computers, as well as Web sites for cellular telephones.
Generally, in the browser function of the cellular telephone, communications are performed with a content server on the Internet according to the HTTP protocol via a mobile communication center having the gateway function to obtain content (hereinafter, simply referred to as “content”) to display a Web site. In the HTTP protocol, ordinarily, the content can be obtained by repeating a request transmitted to the content server from a cellular telephone that is a client and a response replied to the cellular telephone from the content server in response to the request. The request transmitted from the cellular telephone is issued after receiving a response to the last transmitted request, and thus, is easy to undergo the effect of congestion status of the communication channel. Therefore, when the request and response are repeated under circumstances where the communication channel is congested, there are cases where considerable time is required to acquire the content.
Meanwhile, in HTTP/1.1 (RFC2616) that is the Internet standard, it is determined that requests transmitted from a client are pipelined (request pipeline). This request pipeline is a technique of continuously transmitting a plurality of requests without waiting for respective responses. By using this request pipeline, instead of waiting to transmit the next request until a response to the last request has been returned, it is possible to continuously transmit requests without waiting for the responses, and it is thereby possible to reduce the time required to transmit the requests, and shorten the time taken to acquire the content.
To execute the request pipeline, the content server needs to support HTTP/1.1. When the content server does not support HTTP/1.1, the request and response are repeated as described above. Then, an improved data communication method has conventionally been proposed to enable communications between a user apparatus and server apparatus to be performed according to the HTTP protocol even in such a case that the content server does not support HTTP/1.1 In one data communication method, a proxy server converts the version of the HTTP protocol when the content server does not support HTTP/1.1, and HTTP protocol communications are thereby guaranteed between the user apparatus and content server.